In cloud-to-ground lightning (see photos), a "leader" starts in the cloud, sending a hot, negative charge downward. If the electrical field on the ground is strong enough, a positive charge rises up to meet the leader, completing an electrical circuit that is visible as a lightning bolt.

Scientists can already trigger lightning with rockets. But the process is cumbersome and only works about half of the time, according to Joseph Dwyer, a professor of physics and space sciences at the Florida Institute of Technology who was not involved in the study.

Typically, Kevlar-coated copper wire coils are attached to rockets that are launched into storm clouds.